This invention refers to multi-refillable spray cans with a cylindrical body and tapering neck portion which is closed by means of a valve disk receiving the spray valve by which valve disk the spray fluid is filled into the can under pressure. Moreover, this invention refers to a device for filling such cans and a method for manufacturing such cans.
Spray cans (the expression .sub." cans" also covers equivalent containers such as bottles) of the one-way type are very common and are used for receiving most different spraying liquids. The disadvantage of such cans is to be seen in that the empty cans are to be dispensed with, bearing in mind that with a large number of one-way cans the propellant gas is environmentally damaging.
Furthermore, multi-refillable cans are known which are made of a solid and heavy metal body, and which are designed for very high pressures. The armatures of such spray cans in general are made from solid brass and are expensive so that in view of the high production costs the consumer is not interested in using an expensive multi-refillable can instead of a one-way can. So far as such multi-refillable cans are acceptable from the cost point of view, an economical way of use is prevented by the facts that the empty cans are to be collected, are to be transported to a filling station, are to be refilled by using filling machines, and are to be retransported to the consumer which means a considerable expenditure in cost and time so that altogether using such multi-refillable spray cans is not or hardly not competitive. Besides of the cost for transport the main reason why such system is not successful, is to be seen in that any time such multi-refillable cans are filled with spray fluid they must be filled with propellant which, as the pressures of the fluid and the propellant within the can are to be balanced for a correct and competitive filling method requiring large systems.
From EP 0 078 936 B1 a pressurized can for spending industrial foams consisting of a foamer and a propellant is known. The can comprises an inverted bottom, a dome-type upper portion with locking means for discharging the foamer through a valve and a cylinder, within the wall of which a floating cylinder is arranged. The foamer filling is enclosed by the upper side of the piston, an upper length of the cylinder, the dome and the locking means. The propellant is arranged within a propellant space formed by the piston, a lower length of the cylinder and the can bottom. The can bottom receives a one-way valve. The piston floats up on the propellant filler. The space receiving the foamer is provided with locking means having a rubber seal of a valve. The valve body is of tube-like shape and is closed at the inner end by a valve disk which caused by the inner pressure contacts the rubber seal. If the valve body is tilted and, therefore, the valve disk is lifted, the content of the can discharges through one or several openings. The propellant is inserted from downwards through a radial opening and the valve. In order to improve the sealing effect at the valve insert (inner sealing), a cap is provided forming an outer sealing. The cap has a ring-like rubber seal.
The propellant fluid, which is a propellant gas used for this type of pressurized can, is an environmentally damaging propellant gas common for this technique so that with a can of this type the problems existing with common propellants cannot be overcome. Furthermore, the can is not designed for being refilled so that the problems caused by dispensing such cans cannot be solved.
From DE-U-90 06 569.7 a can with pressurized fluid with a foil bag is known which comprises a cylindrical container with a bottom portion and a head portion with valve. Within the lower area and beyond the piston a foil bag is arranged. Said foil bag includes the propellant. Said propellant is entrapped within the foil bag sealed against diffusion in a solid or liquid aggregate condition, and for example is CO.sub.2. The piston can be a laminated piston of the type of a labyrinth sealing, whereby the lamellas are filled with sealing or blocking liquid. It can also be sealed against the can wall by means of an O-ring seal. This type of pressurized can also operates with environmentally damaging propellant and is not refillable.
It is an object of this invention to propose a spray can formed as a monoblock can (the expression .sub." spray can" in the context of this invention also covers can-type or bottle-type spray containers so that in the following description and within the claims the general expression .sub." cans" is used) of the type according to this invention, and to design a can so that it can be repeatedly filled, and is ready to be filled in its empty condition at any time, which means that it can be filled with filling material, that a propellant can be used which is available at any time and at low cost, and that it is free of environmental problems and also is not burnable.
A further object of this invention is to provide a device and a method for first-time and repeatedly filling such cans in a most simple manner, especially to offer very small filling stations and to have the possibility of individually filling such cans.